Hydrofluorocarbons (HFCS) are of current interest due to their potential to replace ozone depleting chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) which are used in a variety of applications including refrigerants, propellants, blowing agents, and solvents. The compound CF.sub.3 CHFCH.sub.2 F (1,1,1,2,3-pentafluoropropane or HFC-245eb) has physical properties, including a boiling point of about 20.degree. C., which makes it particularly attractive as a blowing agent or propellant. Ger. Omen, DE 3,903,336, 1990 (EP 381 986 A) states that fluorinated propanes may be used as a propellant or blowing agent. The use of HFC-245eb as a heat transfer agent is also mentioned in Japanese Kokai Tokyo Koho JP 02,272,086 (Chem. Abstr. 1991:114, 125031q).
HFC-245eb has been synthesized via the catalytic reduction of (1,1,1,2,3-pentafluoropropane CF.sub.3 CF.dbd.CHF) as reported in Chem. Abstr., 1966, 64:578e, Chem. Abstr., 1961, 55:349f, and Chem. Abstr., 1959, 53:1102c. The required olefin, CF.sub.3 CF.dbd.CHF, was prepared by dehydrofluorination of CF.sub.3 CHFCHF.sub.2 with KOH, which in turn, was prepared by reduction of commercially available hexafluoropropene. HFC-245eb was also identified as a minor product (less than 1% yield), in the reaction of 1,2-difluoroethylene and trifluoroacetaldehyde (J. Chem. Soc. Perkin Trans. I, 1980, 2258).
However, the dehydrofluorination of CF.sub.3 CHFCHF.sub.2 (HFC-236ea) is not amenable to large scale manufacture. Fluorine values are lost in the preparation of CF.sub.3 CF.dbd.CHF and a considerable amount of by-product wet potassium fluoride is formed.
It is thus an object of this invention to provide a means of manufacturing 1,1,1,2,3-pentafluoropropane which avoids the above-mentioned shortcomings and which is economical and amenable to large scale, using readily available raw materials.